Triethylamine → 5-(1-methyl-4-nitro-1H-pyrazol-5-yl)-5,8-diazaspiro[2.6]nonane

Participants

Reaction Conditions

Reaction Steps

To a solution of 5-chloro-1-methyl-4-nitro-1H-pyrazole (323 mg, 2.0 mmol), triethylamine (0.7 mL, 5.0 mmol) and potassium fluoride (581 mg, 10.0 mmol) in dry DMSO (20 mL) was added 5,8-diazaspiro[2.6]nonane dihydrobromide (686 mg, 2.4 mmol) and the mixture was heated in the microwave at 65° C. for 4 hr. The mixture was diluted with EtOAc (30 mL) and washed with saturated aqueous NaHCO3 (3×20 mL). The aqueous layer was further extracted with DCM (3×20 mL) and the combined organic layers passed through a phase separation cartridge and concentrated under reduced pressure. The residue was loaded onto an SCX-2 column which was washed with MeOH and eluted with 3% 7M ammonia in MeOH/DCM and concentrated under reduced pressure to give 5-(1-methyl-4-nitro-1H-pyrazol-5-yl)-5,8-diazaspiro[2.6]nonane as a yellow gum (153 mg). To a solution of this intermediate in DCM (10 mL) was added di-tert-butyl dicarbonate (157 mg, 0.72 mmol) and DMAP (4 mg, 0.03 mmol) and the mixture stirred at room temperature for 2 hr. The mixture was washed with water (3×10 mL) and the organic layer separated, passed through a phase separation cartridge and concentrated under reduced pressure to give tert-butyl 8-(1-methyl-4-nitro-1H-pyrazol-5-yl)-5,8-diazaspiro[2.6]nonane-5-carboxylate as a yellow gum (200 mg, 28% over two steps). 1H NMR (400 MHz, CDCl3) δ 8.02 and 8.00 (2s, 1H), 3.85-3.77 (m, 3H), 3.75-3.67 (m, 2H), 3.47-3.27 (m, 4H), 3.29-2.97 (m, 2H), 1.49 (s, 9H), 0.73-0.55 (m, 2H), 0.47-0.38 (m, 2H).

Provenance & Evidence